In general, a chemical mechanical polishing (CMP) apparatus includes a dressing module that dresses (sets) a surface of a polishing pad on a polishing table with a dresser to prevent a decrease in polishing rate, an occurrence of scratch, and an occurrence of dust.
For example, a sweep-type dressing module dresses the surface of the polishing pad by sweeping the polishing pad with the dresser while rotating the dresser. At this time, the CMP apparatus rotates the polishing table at a constant number of revolutions. Therefore, when the dressing is performed by the sweep-type dressing module, a relative linear speed between the polishing table and the dresser changes between the dressing that is performed at the center of the polishing table and the dressing that is performed at the periphery of the polishing table. Specifically, the relative linear speed between the polishing table and the dresser becomes slow at the center of the polishing table, and becomes fast at the periphery of the polishing table.
If the polishing pad is dressed, a surface roughness of the polishing pad is increased, so that the polishing performance of the polishing pad is improved. However, when the dressing is performed by the sweep-type dressing module, the surface roughness of each portion of the polishing pad is changed according to the relative linear speed between the polishing table and the dresser. Therefore, in-plane variation of the surface roughness of the polishing pad occurs due to an difference in the relative linear speed between the center and the periphery of the polishing table. As a result, when a wafer is polished with this polishing pad, in-plane variation of the polishing rate of the wafer may occur, and a polishing temperature of the wafer may fluctuate so as to generate a corrosion.